The present invention relates to a method and a device for attenuating the noise generated at the outlet of an exhaust line.
Eighty percent of the noise emitted by a motor vehicle powered by a heat engine is caused by the engine. The exhaust system of the vehicle therefore has to be designed to reduce the sound level detected by residents.
The provision of an active noise control device in the exhaust line is known. This device allows the noise that is to be attenuated to be neutralized by causing interference between the noise to be attenuated and a counter-noise, which has the same frequency and the same amplitude but is in opposition of phase. The counter-noise is produced electronically using signal processing algorithms, in order to generate destructive interference with the noise to be attenuated.
The sound wave forming the counter-noise is generated by electromagnetic loudspeakers. In the known solutions, the loudspeakers directly produce a sound wave having the characteristics of the counter-noise. In order to be effective, said loudspeakers have to have an electrical power from 100 to 150 W and a mass of between 2 and 4 kg.
The current active noise control solutions are therefore relatively heavy and bulky.